hugo
There are major differences between the Liquidware antipasto version and version 0018. Both can be made to work well. I do a most of the development work on the touchSlide drivers and I have 3 different versions of the Arduino on my machine. For the Mega/Duemilanove version 0018 will be easier for you.
I have some documentation on the slide at
http://coewww.rutgers.edu/~msproul/arduino/
In your code, you dont need to set the pin modes for rxPin and txPin, mySerial.begin will take care of that.
Mark